A New Method for Vertical Growth of Silicon Nanowire in the Vapor-Liquid-Solid (VLS) Process

摘要

A series of silicon nanowires were grown uisng the vapor-liquid-solid (VLS) process in an effort to produce nanowires aligned vertically to the subsrate by varying the chemical properites that are in contact with silicon substrate. In contrast to the conventionally used method in which SiCl_4 is used to remove silicon oxide and to produce vertical silicon nanowires, in this report chemical modification was carried out to produce vertical silicon nanowire. Gold nanoparticles (60 nm and 80 nm) were used as catalyst. Poly-L-lysine (PLL) was used in between the gold nanoaprticles and silicon substrates. The attchment of the gold nanoparticles on the silcon substrate was confimred by SEM images. The oxide layer on silcon surface was either treated with buffered oxide etchant (BOE) or HF. In another case some chemical modification was done on PLL before applying on the silicon surface. The growth of the nanowrie was processed using the temperature below 550 °C. Although not in perfect vertical, the nanowires treated with BOE and HF showed tendency toward vertical direction. Better control in the vertical direction was accomplished with the nanowires produced using the chemically modifed PLL.